Frost dates for 49920Crystal Falls, MI
The average last spring frost in Crystal Falls is June 6 and the average first fall frost is September 9, giving a typical growing season of about 94 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Jun 6
- Average first fall frost
- Sep 9
- Growing season
- 94 days
Safer after Jul 7 (1-in-10 risk)
Possible by Aug 20 (1-in-10 risk)
Last frost typically in 222 days
Frost risk by date
NOAA reports frost dates as probabilities. The middle date is the average (a 50% chance). For spring, the 10% date is a safer planting date: frost after it happens in about 1 year in 10. Light frost (36°F) can damage tender plants; a hard freeze (28°F) kills most annuals.
| Temperature | Last spring: 90% / 50% / 10% chance | First fall: 10% / 50% / 90% chance | Growing season (50%) | Years with at least one |
|---|---|---|---|---|
| Light frost (36°F) | — | — | 58 days | 100% |
| Frost / freeze (32°F) | May 23 · Jun 6 · Jul 7 | Aug 20 · Sep 9 · Sep 27 | 94 days | 100% |
| Hard freeze (28°F) | May 6 · May 24 · Jun 8 | Sep 7 · Sep 25 · Oct 9 | 124 days | 100% |
Planting calendar for Crystal Falls
Planting windows from the University of Maryland Extension calendar, shifted to your average frost dates. Use them as a starting point and adjust for seed packet instructions and local conditions.
| Crop | Task | Window |
|---|---|---|
| Tomatoes | Start seeds indoors | May 6 – Jul 12 |
| Tomatoes | Transplant outdoors | Jun 22 – May 20 |
| Peppers | Start seeds indoors | May 6 – Jun 6 |
| Peppers | Transplant outdoors | Jul 6 – Aug 6 |
| Eggplant | Start seeds indoors | May 23 – Jun 21 |
| Eggplant | Transplant outdoors | Jul 6 – Aug 6 |
| Cucumbers | Sow outdoors | Jul 6 – May 30 |
| Summer squash | Sow outdoors | Jun 22 – Aug 6 |
| Winter squash & pumpkins | Sow outdoors | Jul 6 – Aug 6 |
| Snap beans | Sow outdoors | Jun 22 – Jun 22 |
| Sweet corn | Sow outdoors | Jun 22 – May 20 |
| Watermelon & cantaloupe | Sow outdoors | Jul 6 – Aug 6 |
| Okra | Sow outdoors | Jun 29 – Jul 22 |
| Peas | Sow outdoors (spring) | May 6 – Jun 21 |
| Potatoes | Plant outdoors (spring) | May 6 – Jul 6 |
| Onions | Start seeds indoors (spring) | Mar 25 – Apr 21 |
| Onions | Transplant outdoors (spring) | May 23 – Jun 21 |
| Broccoli | Start seeds indoors (spring) | Apr 18 – May 22 |
| Broccoli | Transplant outdoors (spring) | May 23 – Jun 21 |
| Broccoli | Start seeds indoors (fall) | May 10 – May 20 |
| Broccoli | Transplant outdoors (fall) | Jun 9 – Jun 20 |
| Cabbage | Start seeds indoors (spring) | Apr 8 – May 6 |
| Cabbage | Transplant outdoors (spring) | May 6 – Jun 6 |
| Cabbage | Start seeds indoors (fall) | Apr 30 – May 30 |
| Cabbage | Transplant outdoors (fall) | May 30 – Jun 30 |
| Leaf lettuce | Sow outdoors (spring) | May 6 – Jul 22 |
| Leaf lettuce | Sow outdoors (fall) | May 30 – Jul 16 |
| Spinach | Sow outdoors (spring) | Apr 29 – Jun 12 |
| Spinach | Sow outdoors (fall) | Jun 16 – Jul 21 |
| Radishes | Sow outdoors (spring) | May 6 – Jun 26 |
| Radishes | Sow outdoors (fall) | May 30 – Jul 31 |
| Kale | Sow outdoors (spring) | May 23 – Jun 12 |
| Kale | Sow outdoors (fall) | May 23 – Jun 30 |
| Carrots | Sow outdoors (spring) | Jun 6 – Jul 22 |
| Carrots | Sow outdoors (fall) | Apr 30 – Jun 15 |
| Garlic | Plant outdoors (fall) | Aug 30 – Sep 30 |
Where these dates come from
ZIP code 49920 is matched to the NOAA station Amasa 1W, MI, 16.1 km away, at 1,470 ft elevation (89 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Amasa 1W, MI (used) | 1,470 ft | Jun 6 | Sep 9 |
| Florence, WI | 1,300 ft | May 24 | Sep 25 |
| Stambaugh 2Sse, MI | 1,450 ft | Jun 4 | Sep 10 |
| Iron Mtn Ford Ap, MI | 1,149 ft | May 25 | Sep 24 |
Frost dates near Crystal Falls
- Alpha, MI 49902 · last May 24, first Sep 25
- Amasa, MI 49903 · last Jun 6, first Sep 9
- Gaastra, MI 49927 · last Jun 4, first Sep 10
- Channing, MI 49815 · last May 24, first Sep 25
- Stambaugh, MI 49964 · last Jun 4, first Sep 10
- Sagola, MI 49881 · last May 24, first Sep 25
- Caspian, MI 49915 · last Jun 4, first Sep 10
- Iron River, MI 49935 · last Jun 4, first Sep 10
Frequently asked questions
- When is the last frost in Crystal Falls, MI?
- For ZIP code 49920, the average last spring frost (32°F) is June 6, based on NOAA 1991-2020 climate normals for the Amasa 1W, MI weather station. There is a 1-in-10 chance of a frost after July 7.
- When is the first frost in Crystal Falls, MI?
- The average first fall frost (32°F) is September 9. There is a 1-in-10 chance of frost by August 20, so tender plants are at risk from that point on.
- How long is the growing season in 49920?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 94 days long.
- Are these frost dates a forecast?
- No. They are 30-year averages and probabilities from NOAA weather station records. Use them to plan, then watch your local forecast before planting tender crops or leaving them uncovered.